Shall I buy the CO +7 Achromat for my Letus35A? at DVinfo.net

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Old September 20th, 2006, 03:35 PM   #1
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Shall I buy the CO +7 Achromat for my Letus35A?

I thought I'd throw this out to the group, would be grateful for any feedback.

I've been tinkering with my new Letus35A for a week now. I bought the custom-made one for my Sony HVR-A1U, which has a longer barrel than the standard model.

I'm now starting to get some better results (a special thank you to Bob Hart for some excellent advice).

As I perfect my images, I was wondering about whether to upgrade the supplied Achromat and Diopter combination with the CO +7 Achromat.

Reading around these forums, the CO glass seems to be well received, even by such quality-conscious individuals as Dan D.

Anyone have any thoughts before I give B&H another $220? :)

I've also seen the +10 Optek for $60: http://www.opteka.com/productdetail.asp?ProductID=4119

I think this and the CO glass are the only 58MM Achromats with high (over +5 diopter values) that are readily available. The Canon 250D seems good but not quite strong enough (I'm looking to minimize zooming and to do away with any extra diopters and fit directly into my Letus, hence the 58mm).

Particularly keen to hear from other A1U or HC1 owners, especially those with the same custom-made Letus with the longer barrel.

TIA

Last edited by Paul Ramsbottom; September 20th, 2006 at 06:28 PM.
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Old September 20th, 2006, 09:02 PM   #2
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I used mine on my Letus (and GL2 and later, my FX1) and loved it with a passion. Reduced the chroma aberration and distortion a whole bunch. I made earlier posts suggesting that $220 was a bit too much to pay for the quality increase

*but*

I happen to have mine lying around collecting dust (figuratively), which I will sell to you for $120. It's got scratches on the outside metal ring from where the Letus screw dug into it, but optically and functionally, it's flawless. Comes with the end caps as well.

I suppose this is a classified but you mentioned using it and I figure I don't have a use for it anymore so I'd just offer mine up.

The only thing is, I'm at college and I won't be home for another week or so, so I don't know when I'll be around to ship it. Let me know.
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Old September 20th, 2006, 11:29 PM   #3
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Paul.

Because your HC1 version is a custom model, I suggest an email enquiry to Quyen first. He will have more of an idea as to the best power achromat to use for best groundglass imaging area.

From your description of the macro stack on your other post, +7 will probably put you where you want to be. I say this with a caveat. The lenses you use, are they at least f2.8 lenses or better f1.8? If not, you may still have some edge or corner falloff.

The Century will help get you furthur into the centre of the groundglass and inside the hotspot but you may take a resolution hit.

You might have to make some adjustments to camcorder-to-groundglass distance and this is why you should consult Quyen.

Resolution versus edge falloff is a bit of a lottery because the better glass in the Century will give you a sharper image of the groundglass itself so there may be no loss in real terms but there will be a lesser field of view.

I don't know if Quyen uses a condenser in the path anywhere. This is another factor which only he can advise on.

Another advantage is in low light performance. With your cam you need to keep as much as you can. Less zoom-through means less light lost in most instances.

In my circumstance, which is different from your own because I flip the image to camera, the +7 enables me a closer couple to the camcorder with the zoom backed off a little. I can handhold the assembled cam/AGUS35 combination.

Because of the compact prism path I have chosen to use, 30mm width, the +7 has to sit almost on top of the rear prism apex and I still get a constricted path which means usable GG area is about 24mm wide.

A +4 enables me to sit the camera off furthur from the groundglass, stay inside the constriction of the prism path and get a larger image off the groundglass. I then take the penalty of max zoom-through with the light loss and the appliance is about 85mm longer and not so easy to handhold any more.
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Old October 2nd, 2006, 12:14 AM   #4
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Well, nevermind then.
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Old October 2nd, 2006, 01:32 AM   #5
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lol. I already sold Paul my CO achromat. With no scratches. For $120! I guess I'm a nice guy.
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Old October 2nd, 2006, 01:53 AM   #6
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Haha, I hadn't noticed that. Sorry :)
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Old October 7th, 2006, 09:51 AM   #7
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Just letting anyone else know :
http://shopproducts.howstuffworks.co...20/SB-213/SO-1

The Opteka 10X Pro macro is only $30.00 at the link above.
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Old October 7th, 2006, 02:27 PM   #8
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David that macro is not an achromat which means it is not a two-piece macro. These kinds like the opteka are usually cheap, around the price you stated, and suffer from distortion and mainly chroma aberration.
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Old October 7th, 2006, 05:55 PM   #9
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Ben,

I was merely pointing it out because Paul had mentioned it for $60.00 earlier in the thread. ;)
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Old November 1st, 2006, 07:45 AM   #10
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CO+7 or CO+4 for FX1 ?

Hi
I'm going to upgrade my 58mm version of Letus35A with Century Optics achromat. Could someone tell me which achro is better, +7 or +4? I have FX1 with 72-58 step-down ring.

Thanks

Last edited by Anton Galimzyanov; November 1st, 2006 at 09:21 AM.
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